Electric-arc welding apparatus



July 12, 1927. 5,208

J. H. EZENDAM ELEQTRIC ARC WELDING APPARATUS File Ja 2 1926 2Sheets-Shet 1 ,b. 4 v

a f/ rg July 12,1927. 08 J. H. EZENDAM ELECTRIC ARc WELDING APPARATUS ld Jan, 2, 1926 2 Sheets-Sheet 2 Patented July 12, 1927.

UNITED STATES PATENT OFFICE.

JAN HENDRIX EZENDAM, OF AMSTERDAM, NETHERLANDS, ASSIGNOR TO N. V'. IN-DUSTRIE-EN HANDELMAATSCHAPPIJ' V. H. HARMS &; (10., OF AMSTERDAM, NETH-ERLANDS.

nLEorRIo-Ano WELDING APPARATUS.

Application filed January 2, 1926, Serial No. 78,941, and in theNetherlands December 30, 1924.

The British specification of Patent No. 12,724 A. D, 1910 relates toelectric arc-welding apparatus, in which thei'e is provided a shuntcontaining an auxi iary resistance across the branches of the weldingcircuit, said shunt being put in and out of circuit al ternately withthe' welding are. In this known apparatus. the shunt is opened andclosed under the influence of an electromagnet, the coil of which istraversed by' the welding current. Ifsaid elcctromagnet is energizedwhen welding is being performed, it opens the shunt, but when the arcbreaks, the coil of the electromagnet is deenergized, the core falls bygravity and the auxiliary resistance is again included in the circuit.

The present invention also contemplates the automatic putting in and outof the auxiliary resistance, but according to the invention this objectis attained by'novel means,

which have specific advantages over the known art.

In accordance with the invention, the closure of the circuit comprisingthe shunt with the auxiliary resistance. is not controlled by thecomparatively rough means constituted by the interruption of the weldingcurrent, but under the influence of the tension, which varies during theprogress of the work. The

, coil of the electromagnet, which controls the switch of the shunt isnot, therefore, placed inthe welding circuit, but it is connected atboth ends to the voltages at either side of the welding arc, wherebydifi'erent advantages are realized. In the first place, the

closure of the shunt comprising the auxiliary resistance takes placeswhen the electromagnet is energized, that is to say, in a more reliablemanner than inthe known appara tus, in which said shunt-is closed by theweight of the core of the electroma'gnet when the latter is dead. Asecond advantage is, that the coil 'of the electromagnet is nottraversed by the strong welding currents, but that it is supplied withcurrent,

the strength of which can be controlled at will. The most importantadvantage, however, results from an embodiment of the invention such,that the voltage or pressure magnet already becomes operative before thewelding are is broken, i, e. before the voltage has suddenly risen to ahigh value. Said embodiment is based upon the fact,

' mined limit.

that when welding is being performed, the voltage is to a certain.extent proportionate to the variable length of arc-except of course withmachines arranged to maintain a substantially constant tension. Thevoltage coil can be made in such a manner as to complete the shuntcircuit comprising-the auxiliary resistance at the moment, wherein thelength of the welding arc, and, consequently, the voltage exceeds apredeterlVith these means it is impossible to perform welding with anexcessively long are (which,-as is known in the art, does not givesatisfactory results) as the inclusion of the auxiliary resistance in(the welding circuit momentarily-results in the interruption of the are.

Figs. 1-5 of the drawing illustrate diaprises the auxiliary resistance 6and the contacts 7 and 8, is in shunt to the arc, said contacts beingadapted to be bridged by a bridging member 9. Said member is secured tothe core 10 of an electromagnet, the coil 11 of which is connected tothe conductors 2 and 3.

Fig. 1 shows the apparatus in the position when the welding proceeds.The voltage across the conductors 2 and 3 is so low, that the attractionexercised. by the coil 11 is insufiicient t0 raise the core 10 and themember'9 to complete the shunt 5. If, however, said voltage rises toapredetermined value either before or after the interruption of the arc,the influence of the coil 11 on the core 10 is sulficient to strike themember longer support the core 1O with the member 9 and the shunt 5is-reopened.

- The novel automatic switch can also be combined with the prior meansin the manner as illustrated in Fig. 2.

The parts I to 11 correspond to those in Fig. 1. The contacts 7, 8,however, are

' adapted to be bridged. besides by the. men'iber 9, by a bridgingmember 12 secured to a. core 13. the coil of which is placed in thewelding circuit so as to be supplied with the welding current. \Vhen theweldingapparatus is connected to the. source of current, both members 9and 12 bridge the contacts 7 and 8 as long as welding is not beingperformed and the auxiliary resistance 6 is then put in circuit. At themoment wherein the welding place is short circuited, coil 14 isenergized and the encrgization of coil 11 is cut down. The member 12 issuddenly raised and tbc n'icmber 9 falls by gravity. The connectionbetween the contacts 7 and S -is thereby broken and the auxiliaryresistance is cut out.

In this embodiment, the. strength ot' co l 11 should be so chosenrelative to the weights of the member 9 and ot the core 10, that thelatter will be raised to bridge the contacts 7 and 8 through the member11 it, during the welding operation, the length of the are exceeds acertain limit and the voltage thereby rises to a nedetermined value. Atsuch moment the arc is extinguished by the inclusion of the auxiliaryresistance 6, whereby coil 14 is deenergized, core 18 falls by gravityand member 12 bridges the contacts 7 and 8. As compared with theembodiment shown in Fig. 1, this arrangemento-fl' ers the advantage ofgreater reliability as far as the inclusion of the auxiliary resistanceis concerned, for if coil 11, due to any cause, should fail to operateas desired, coil 14 will switch in the auxiliary resistance immediatelyafter the arc is broken.

In this respect the embodiment illustratedin Fig. 3 is still preferable.In this embodiment. both coils ll and 14'envclopc a common core 13. Whenenergized, coil 14 tends to raise the core 13, but. it is counteractedby coil 11, by the weights of core 1 and bridge 12, and by the tensionof the spring 15. The strengths of both coils are so proportionated,that when the welding is started, i. e. when the arc is being drawn,the. short circuit current traversing coil 14 pulls the core 13 and themember 12 upwards. During the progress of the work, when the strength ofthe current is reduced and the tension has increased, a. certainequilibrium is established between the forces acting upon the core 13,which, consequently, remains floating.- If the length of the arc exceedsa predetermined limit, the'voltage coil 11 prevails, so that it pullsthe core 13 down and as soon as the member 12 bridges the contacts 7 and8, the resistance 6 is put in circuit and the arc is extinguished. Atthe same moment both coils are deenergized, coil 11 because it shortcircuited by the member 19, coil 15 because of the opening of theWelding circuit in which it is placed.

esaaos he spring 15 can be provided with tension adjust ing means,whereby the voltage atwhich the arc is broken can be regulated.

The arrangement shown in Fig. 4 also comprises two coils in oppositionto each other. (oil 11 again forms a voltage coil and envelopes the core10, whereas coil 14, placed in the welding circuit, envelopes the core13. The coil 14 having a high ohmic resistance also forms a. Voltagecoil. Also enveloping core 13 and placed in the welding circuit is asecond coil 16. (oils 14 and 16 are connected in parallel to theconductor 2 so that, when the coil 16 is cut in, the coil 14- ispractically short circuitcd. The coil 16 is only supplied with currentfrom contacts 17. 18 and lead 19 when said contacts are bridged by themember'Qtl.

'lhe ,modus operandi of this automatic switch is as follows:

The figure shows the apparatus in the position. wherein the same isconnected to a transformer but wherein no welding is being performed. Itnow contact is made at the welding place 4, coil 14 is energized. Atthis moment, said coil is not yet opposed by coil 11, because the latteris short-circhited,

so that the bridging member 20 is pulled upwards. Concurrently, theconnection between the contacts 7 and Sis broken, whereby the resistance(3 is almost completely cut out, but said resistance is still traversedby the current, which now energizes coil 11. This coil now coi'mtcractscoil 14, whereby the movement of the bridging member is braked and theimpact resulting from the said member striking against the contacts 17.19 is damped. tacts are interconnected, the coil 16 is switched in andthe welding current is closed. The bridging member 20 is now held inengagement. with the contacts by the action of the coil it), whereascoil 11 is short-circuited so that. there is no current in it. In thisposition of tho di'ti crent parts welding can proceed. 1

It, owing to an excessive length of arc, the voltage rises to apredetermined limit, the coil 1.1 prevails so that it pulls the member20 downward and the connection between the contacts 17 and 18in thewelding circuit is broken. As a consequence. the arc is momentarilyinterrupted both coils 14 and 16;

are deenergized and coil 11, the strength of which still increases for ashort time owing to the rise of voltage, retracts the bridge 20..

At the moment, wherein these conis short-circnited and;

as a rule, is dangerously high. This, however, is only a disadvantage ascompared with other embodiments of the invention. for instance, the oneillustrated in Fig. 3, but not in con'iparison with known apparatuscomprising an automatic switch, which uts the auxiliary resistance incircuit owing to the interruption of the arc.

Fig. 5 still shows the diagram of a welding apparatus, which also hasthe advantage that the coil 11 does not hesitate when the auxiliaryresistance is switched in, but in which no zero load voltage can occur.

The parts 120 correspond to those shown in Fig. 4. The magnet 11 here isprovided with a fixed core 10 and with an armature 21 secured tothe onearm of a lever 22, which is fulcrumed as at 23 and the other arm ofwhich is loaded by a spring 24. The left hand side end of this lever isconnected through a rod 25 to a bridging member 26 adapted to bridge thecontacts 27 and 28, the latter being permanently connected to thecontacts 7 and 8 through the leads 29 and 30, respectively.

The installation is illustrated in welding position. If the length ofthe welding arc exceeds a predetermined limit, the magnet 10, 11overcomes the action of the spring 24, so that the armature 21 isattracted by the magnet with a rapidly increasing force and theccontacts 27 and 28 are bridged by member 26. As a result,auxiliary'resistance 6 is switched in, ,which again causes the arc tobreak. Thereafter c0il16 dies, the connection between contacts 17 and 18is broken and that between contacts 7 and 8 established.

What I claim is '1. In an electric arc-welding apparatus, a weldingcircuit, a shunt circuit across the welding circuit including aresistance, elec- 2. In an electric arc-welding apparatus, a weldingcircuit. a shunt circuit across the welding circuit including aresistance, electromagnetic means for opening and closing the shuntcircuit, the energization of the electromagnetic means being dependentupon the voltage across the welding are, said electromagnetic meansincluding an electric element energized by the voltage and acting toopen the shunt circuit, and a second electric element acting in the samesense as the first electric element and energized by the weld ingcurrent in response to energization of said first electric element.

3. In an electric arc-Welding apparatus, a welding circuit, a shuntcircuit across the welding circuit including a resistance.electromagnetic means for opening and closing the shunt circuit, at twopoints in parallel relation to each OthGIyELt one point under theinfluence of the welding current and at the other point under theinfluence of the voltage, said electromagnetic means including anelectric element energized by the voltage and acting to open the shuntcircuit, and a second electric element acting in the same sense as thefirst electric element and energized by the welding current in responseto energization of said first electric element. In testimony whereof Iafiix my signature.

JAN HENDRIK EZENDAM.

